JPS636621A - Coordinate input pen - Google Patents

Abstract

PURPOSE:To improve the temperature characteristics and the stability by using a sintered compact having high strength obtained by sintering the green compact to form a horn part of a coordinate input pen. CONSTITUTION:A coordinate input device consists of a vibration transmitter 2, a vibration pen 5 for input of coordinates, a pulse signal generator 10, an operational amplifying circuit 11 which detects the position coordinates of a contact point 3, etc. For this coordinate input, the start signal received from the circuit 11 is sent to the generator 10 and the pulse electric signal is applied to the pen 5. Then vibrations are given to the transmitter 2 from the point 3. The delay time due to said vibrations is detected and the coordinates are calculated by the circuit 11. A horn part 1 of the pen 5 is made of ceramics, e.g., a sintered compact obtained by sintering an alumina green compact, etc. Thus the pen 5 excels in the wear resistance and can designate an accurate position.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a coordinate input pen, and particularly to a coordinate input pen used in a coordinate input device that propagates elastic waves and detects the position where the elastic waves are generated. .

[Prior Art] The pen tip of the vibrating pen used in conventional devices of this type is made of metal, and when the input panel is made of a hard material such as glass, when the vibrating pen is connected to the input panel and used,
The tip of the horn (pen tip) often wore out and became deformed.

Figure 7(a) shows when the tip of the horn is normal;
FIG. 7(b) shows a state in which the tip of the horn is worn and deformed. In the figure, 7o is a horn (pen tip), 2 is a vibration propagation body which is an input panel, and 3 is a contact point between the horn 70 and the vibration propagation body 2.

By the way, in order to find the specified position coordinates (the position of the contact point 3) using elastic waves, the elastic waves propagating radially from the contact point 3 are connected to at least two vibrations provided at predetermined positions. By measuring the delay time until detection by the detection piezoelectric element, the contact point 3
The position on the vibration propagation body 2 is calculated.

[Problems to be solved by the invention] Therefore, as explained earlier, when the horn (pen tip) is deformed, the resonance frequency of the horn changes, so there is a "shift" in the imaging frequency propagating from the tip of the horn. This will occur. Furthermore, the tip of the horn becomes deformed and uneven, and even if you move the vibrating pen uniformly, not only does the contact point not move uniformly, but the vibrations emitted from the tip of the horn become unstable, causing contact This was a factor that reduced the accuracy of position detection of point 3 (the tip of the vibrating pen).

Furthermore, when manufacturing a metal horn with high dimensional accuracy, each horn must be cut individually, resulting in high costs and poor productivity.

The present invention has been made in view of such prior art,
An object of the present invention is to provide a coordinate input pen that can calculate coordinate positions with high accuracy by improving the wear resistance of a horn that is the nib of the coordinate input pen.

Another purpose is to make it possible to improve the productivity of the horn.

[Means for Solving the Problems] In order to solve this problem, the present invention has the following configuration.

That is, the coordinate input pen designates a desired position on a coordinate input board and energizes the coordinate input board to generate an elastic wave, and at least the nib of the coordinate input pen is made of ceramics.

[Operation] In the configuration of the present invention, a coordinate position is specified using a coordinate input pen having a ceramic nib.

[Example] Hereinafter, practical examples of the present invention will be described in detail with reference to the accompanying drawings.

First, an overview of the coordinate input device in this embodiment will be explained.

FIG. 3 is a configuration diagram of the coordinate input device of this embodiment.

In the figure, 5 is a vibrating pen (coordinate input pen), and a piezoelectric element 6 (second
(see figure) and a horn 1 that amplifies the vibrations. 4 is a tablet-type signal input board, and 2 is a vibration propagation body. 3 is a contact point between the horn 1 and the vibration propagation body 2. Further, 7a to 7C are piezoelectric elements for vibration detection, which convert elastic waves into electrical signals. 8 is a lead wire; 9 is a vibration absorbing material for preventing reflection of elastic waves; 11 is a lead wire 8 that instructs the pulse signal generator 10 to generate a pulse signal;
This is a width calculation circuit that receives an electrical signal from the contact point 3 and detects the position coordinates of the contact point 3.

To explain the operation in the above configuration, first, increase 4Ii
A start signal is output from the arithmetic circuit 11 to the pulse generator 10, and in response, the pulse generator 10 generates a pulse electric signal. As this frequency becomes higher, the resolution increases, but the attenuation rate also increases, so 300 to 500 KHz is appropriate. In response to this electrical signal, the piezoelectric element 6 of the vibrating pen 5 expands and contracts (vibrates) at the frequency. This vibration is amplified by the horn 1, and the vibration is transmitted to the vibration propagation body 2 at the contact point 3, where it propagates as a plate wave elastic wave. Note that the material of the vibration propagation body 2 may be a transparent plate such as glass or acrylic.

Now, the propagated plate wave elastic wave is detected as a piezoelectric voltage by three piezoelectric elements 78 to 7c provided for vibration detection, and is sent to the amplification calculation circuit 11 via the lead wire 8. At this time, the delay time required for vibration propagation is detected in synchronization with the start signal generated from the amplification calculation circuit 11. The above operation is repeated, for example, 50 to 150 times per second, and the piezoelectric elements 7 for vibration detection at three locations are obtained.
The position coordinates of the contact point 3 of the vibrating pen 5 are calculated using the delay times a to 7c.

Note that this calculation method is shown below.

As shown in FIG. 2, the position coordinates of the vibrating pen 5 are (x, y)
and the coordinates Pa to Pc of the three piezoelectric elements 78 to 7C for vibration detection are Pa (xz, Xl) = (o
, O)Pb (X2.X2)= (X2.O)Pc
If (X3.X3) = (0, ya), then the vibrating pen 5
The position coordinates (x, y) of are obtained using the following equation.

However, the position coordinates of the vibrating pen 5 can be obtained by performing calculations of t1 to t3: propagation time of the elastic wave (V) - propagation velocity of the elastic wave or more in the amplification calculation circuit 11.

Note that when the vibration during vibration propagation 2 reaches the vibration absorbing material 9,
The amplitude of the elastic wave is attenuated here. In this embodiment, the vibration absorbing material 9 is made of silicone rubber mixed with metal powder in order to have a large attenuation rate and match the natural acoustic impedance of the glass 9, but the material is not limited to this. It's not something you can do. Furthermore, regarding the plate thickness of the vibration propagation body 2, it is appropriate that the thickness be 0.3 to 2.0 mm. This is because as the plate thickness decreases, the amplitude of the propagated and detected elastic waves increases, but the strength of the material decreases.

Vibrating pen 5 in the coordinate input device of this embodiment as described above
A case where the horn 1 is made of ceramics will be explained with reference to FIGS. 1 and 2.

FIG. 2 is a sectional view of the vibrating pen 5 near its tip. In the figure,
6 is a piezoelectric element that vibrates in accordance with the frequency of the signal when it receives a pulse signal, and this vibration causes the flange 1 to vibrate.
Horn 1 fixed to 2 or integrally formed with flange 12
It becomes an elastic wave and is transmitted to the vibration propagation body 2.

In this embodiment, as a specific example of the ceramic material, a sintered body obtained by sintering a molded alumina powder is used. Alumina can be produced relatively easily into high-density sintered bodies with high strength and good dimensional accuracy, and is one of the most versatile materials among ceramics.

Further, in this embodiment, the shape of the horn 1 is an exponential shape. The exponential shape refers to a shape whose curve changes exponentially, and the horn 1 shown in FIGS. 1 and 2 is of this type.

In addition, in the figure, A is the large end face of the horn, B is the small end face of the horn,
C is the tangential straight line, Dl is the diameter of the large end face of the horn, D
2 is the diameter of the small end face of the horn, 1 is the length of the straight part of the horn, 2 is the length of the exponential part of the horn, X is a predetermined distance from the large end face A, and Dx is the horn at the distance aX. is the diameter of

Further, it is desirable that the flange 12 be located at a node of the vibration amplitude of the horn 1. The reason is that supporting the nodes of the vibration width has the least loss of vibration energy and is more efficient. Flanges made of alumina have great strength, so they have the advantage of being thinner and reducing loss of vibration energy due to the support.

Now, the resonance frequency f is 400 [KHz], D1-5
．． 0 [mml.

If D2-0.5 [mm], then 11-6.14
[mm], l 2-12.29 [mm], D
β (exponent) of x-Je-/'' [mm] is 0.187. This value is determined by the following resonance conditional expression (1) and the position XN of the vibration nodal surface in (2). Equation, and (3)
It can be derived from the formula for determining the amplitude expansion rate of the formula.

The main symbols used here are summarized as follows.

Sl: Area of the large end of the horn S2: Area of the small end of the horn Dl: Diameter of the large end of the horn D2: Diameter of the small end of the horn! 11: Length of the straight part of the horn! 12: Length of the exponential part of the horn α: Wavelength constant = w/c C: Sound velocity in the horn material (longitudinal wave in the alumina rod:
9.65x 103 [m/5eclf: Resonant frequency of the horn W: Resonant angular wave number of the horn = 2πf 1) In the equation, α=W/c.

tan (a-x s) = 1 / jan (a-
l +) - (2) (α・S, depends on the straight part when 〉π/2) When horn 1 is designed with 1/2 wavelength resonance as described above, the speed of sound is higher in alumina than in metal. Quite fast (alumina: approx. 9800+n/sec, aluminum 500
0/Sec c), the length of the horn 1 is longer in alumina. Incidentally, the diameter D1 of the large end face of the horn cannot be made very large, because if it becomes close to half a wavelength or larger, radial resonance will occur. In this sense, the diameter of the large end face can be made larger when the horn 1 is made of alumina and has a longer length than when made from metal. Therefore, there is an advantage that the degree of freedom in dimensional design of the vibrator (piezoelectric element 6) attached to the large end face of the horn 1 is increased, and vibrators having various frequency characteristics can be employed.

;= FIG. 5 shows the manufacturing process of the horn 1 shown in FIG. 1.

Here, a specific example will be described in which the raw material is alumina.

First, the raw material alumina is finely ground, and additives (impurities) are
Mix and granulate. Once granulated, it is molded and fired. Finally, it is processed and completed.

The additives include sintering accelerators, metals and non-metals as grain growth control agents, and organic compounds as forming aids. Further, molding includes molding such as pressurization, extrusion, casting, and injection. This manufacturing process is just one example; it is possible to manufacture the flange-body retaining horn part of a high-strength alumina sintered body with a high-strength microcrystalline structure using other manufacturing processes, and the manufacturing process also differs depending on the material. . Furthermore, if the horn portion can be manufactured at the molding 18 and firing 19 stages even if the processing steps are omitted, this will lead to cost reduction.

By manufacturing the horn by sintering alumina as described above, the horn has greater hardness and strength than metal, and the tip of the horn is hardly deformed. In order to increase the strength of the alumina ceramics, it is preferable to reduce the average particle diameter of the compacted powder, reduce the porosity of the sintered body, and suppress the amount of impurities.

Note that the material used in this example is alumina (8120
As explained in 3), in addition to this, zirconia (2r02)
, titania (Ti02), silicon carbide (Sin)
, Si3N4, etc., or may be not only a sintered body but also glass or the like.

Furthermore, the shape of the horn may be other than that shown in this embodiment.

Alternatively, a horn without a flange serving as a supporting member may be used.

Furthermore, the shape of the horn may be conical, exponential, catenoidal, with a straight part connected to the large end face of the horn, or not connected. The horn may be of the stepped) type, step binary type, step exponential type, etc.

In this embodiment, a ceramic horn part is used for the vibrating pen, but it may also be attached to a vibration propagation body and used for vibration detection (senna part). FIG. 6 shows a specific example of this, in which 60 is a ceramic horn, 61 is a piezoelectric element for vibration detection, and 2
8 is a vibration propagating body, 8 is a lead wire, and 9 is a vibration absorbing material.

The tip of the horn 1, which has a piezoelectric element 7 attached to its large end surface, is fixed in contact with the surface of the vibration propagation body 2, and the imaging propagated through the vibration propagation body 2 is detected.

As explained above, in this embodiment, the horn part is made of ceramics, especially a high-strength sintered body made of sintered molded powder, so that the wear of the tip is reduced compared to a metal horn.
Deformation is reduced, good vibration is generated from the horn, and high-precision, high-resolution position coordinate detection is possible. Also, by making the horn ceramic, temperature characteristics were improved and stability increased.

Furthermore, since it can be molded by a casting method or the like, it is possible to manufacture a horn part with a complex shape in which the flange is integrated with the horn with good dimensional accuracy, and it is possible to improve productivity and reduce costs compared to manufacturing by cutting metal.

Moreover, since the strength of ceramic flanges is greater, the flange thickness can be made thinner than that of metal flanges, and loss in image transmission due to support can be reduced.

Furthermore, since the speed of sound (velocity of propagation) of most ceramic powder sintered bodies is faster than that of metals, the length of the horn becomes longer.

Therefore, the diameter of the large end face of the horn can be increased, and vibrators with various frequency characteristics can be attached to the large end face of the horn.

The fact that the diameter of the large end face of the horn can be made larger means that the degree of freedom in the size of the diameter of the large end face of the horn increases, and therefore the setting range of the amplitude expansion rate becomes wider, and also the size of the horn large end face can be increased. This has the effect of increasing the degree of freedom in the shape of the vibrator.

[Effects of the Invention] As described above, according to the present invention, it is possible to obtain a coordinate input bench that has excellent wear resistance and can always specify an accurate position.

In addition, it is possible to improve productivity and reduce costs compared to manufacturing by cutting metal, and since the strength of ceramic flanges is greater, the flange thickness can be thinner than that of metal, and there is no loss in vibration transmission due to support. can be reduced.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the horn of this embodiment, Fig. 2 is a sectional view of the vicinity of the pen tip of the vibrating pen of this embodiment, Fig. 3 is an overall block diagram of the coordinate input device of this embodiment, and Fig. 4 is a diagram showing the relationship between the vibrating pen and the delay time until detecting an elastic wave, Figure 5 is a diagram showing the manufacturing process of the horn, Figure 6 is a cross-sectional view near the piezoelectric element for detecting elastic waves, Figure 7 (a) shows a normal horn, and Figure 7 (b) shows a worn horn.
... Horn, 2 ... Vibration propagation body, 3 ... Contact point,
4... Signal input panel, 5... Vibrating pen, 6... Piezoelectric element, 7a-7c... Piezoelectric element for detecting elastic waves, 8...
... Lead wire, 9 ... Vibration absorbing material, 10 ... Pulse signal generator, 11 ... Width calculation circuit.

Claims (3)

[Claims] (1) A coordinate input pen that specifies a desired position on a coordinate input board and energizes the coordinate input board to generate an elastic wave,
A coordinate input pen characterized in that at least a nib of the coordinate input pen is made of ceramics. (2) The coordinate input pen according to claim 1, wherein the curve in the longitudinal direction of the pen tip is exponentially functional. (3) The coordinate input pen according to claim 1, wherein the position where the pen tip is supported is a node position when vibration propagates through the pen.